Steam trap



Sept 6, 1960 D. R. YARNALL ET AL 2,951,496

STEAM TRAP Filed Feb. 11, 1958 7 Sheets-Sheet 1 flaw 1a? 206a); 5213522! Wzifer 6 zadermn Sept. 6, 1960 D. R. YARNALL ET AL 2,951,496

STEAM TRAP Filed Feb. 11, 1958 'r Sheets-Sheet 5 '57 l if 3% WMQ MWATTORNEYS.

Sept. 6, 1960 Filed Feb. 11,

D. YARNALL T AL STEAM TRAP 7 Sheets-Sheet 5 p 1960 D. R. YARNALL ET AL2,951,496

STEAM TRAP Filed Feb. 11, 1958 7 Sheets-$heet 6 V I; I j/ l K Z W ATTO RN EYS Sept. 6, 1960 D. R. YARNALL ETAL 2,

STEAM TRAP Filed Feb. 11, 1958 7 Sheets-Sheet 7 if I J L United StatesPatent STEAM TRAP Filed Feb. 11, 1958, Ser. No. 714,595

34 Claims. c1. 137-183) The present invention relates to steamtrapswhich are actuated by fluid forces to discharge water and air from asteam system.

T he present application is a continuation-in-part of our fcopendingapplication, Serial No. 662,222, filed 'May 28, 1957, for Steam Trap.

A purpose of the invention is to obtain morepositive actuation of asteam trap from available forces.

A further purpose is to secure greater discharge capacity for a givensize of trap.

Afurther purpose is to produce a steam trap which opens and closes lessabruptly.

A further purpose is to flush away dirt accumulations which wouldinterference with trap operation.

A further purpose is to make the response of a steam trap to particularfluid conditions more consistent.

A further purpose is to employ continuous leakage from the controlchamber to the outlet in a steam trap When the valve is closed, and tocarry leakage fromthe inlet when the valve is closed directlyto theoutlet without flowing through the control chamber.

A further purpose is to employ a iiow passage from a position beyond theinlet to the outlet which is a groove in the valve seat or the valveplate, or both.

A further purpose is to increase the .area under the valvewhich is atdischarge pressure as the fulcrum is i approached.

A further purpose is to use an annular flow passage which is eccentricto the inlet valve disc.

Afurther purpose is to make a flow passage in the valve seat concentricwith the inlet passage.

A further purpose is to provide a flow passage which is a groove in thevalve seat and a corresponding groove in the valve disc, the groovescoinciding at one position and diverging at other positions, theposition of coincidence desirably being that remote from-the fulcrum.

A further purpose is to employ a steam trap valve seat which is aremovable unit seated in the body.

A further purpose is to use a circular valve plate in a circular controlchamber, the valve plate being free to rotate and also tilting.

A further purpose is to employ a finish on the engaging surfaces of thevalve plate and valve seat which in smoothness and flatness permitsleakage clearance between the mating surfaces down to but not belowmicroinches and preferably within the range from 10 to 80'inicroinches.

A further purpose is to use a sealing flat portion .around the inletpassage, and to provide a flow passage including a groove in the valveplate and a groove in the valve seat, the center of the inlet passagebeing offset from the center of the valve plate away from the fulcrum bya distance of approximately /5 the width of each groove and each groovebeing approximately twice as Wide as the sealing flat.

,A further purpose is to provide a line fulcrum on the valve seat.

Patented Sept. 6, 1960 ice A further purpose is to provide a rollingfulcrum merging tangent to a linefulcrum on the valve seat.

A further purpose is to employ a rectangular valve plate.

A further purpose is to use a steam trap valve plate which has acircular recess which engages a circular shoulder forming the fulcrumsurface.

A further purpose is to mount a guiding knob on the side of the valveplate remote from the seat and to guide the knob in a guiding socket inthe control chamber.

A further purpose is to provide continuous leakage from the controlchamber to the outlet by a'groove in the valve plate or by a groove inthe valve seat.

A further purpose is to extend a passage through t-he valveplate fromthe control chamber to the outlet when the valve is open. a

*A further purpose is to provide a hole through' the valve plate fromthe inlet to the control chamberwhen the valve plate is open, the holebeing closed by the valve seat when the valve plate is closed.

.A further purpose is to locate the inlet: passage nearer the center ofa circular control chamber than the outlet passage, the centerof theinlet passage being onthe opposite side of the center of the valve platefrom the outlet passage.

Further purposes appear in the specification and in the claims.

In the drawings we have chosen to illustrate a few 'only of the numerousembodiments in which our inven- 30 operation and clear demonstration ofthe principles involved.

Figure 1 is a central axial section through apreferred ,embodimeritofthe steam trap of the invention, the'valve plate being seated. s

Figure 2 is a plan view of the steam trap of Figure-l with the bonnetand valve plate removed.

Figure 3 is a phantom view similar to Figure 1 ill-ustrating dimensionalrelations which are'important -inexplaining the operation.

Figure 4 is a view similar to Figure 1 showing athe valve plate in openposition.

Figure 5 is a. diagrammatic "plan view'of .thewstea'm trap of Figure 1,illustrating certain dimensional relations which are useful inexplaining the operation.

Figure 6is. a fragmentary diagrammatic plan View of .the steamtrap ofFigure 1 showing the relations of the flow passage tothe remainingparts.

Figure'7 is a fragmentary axial section showingthe preferred dimensionsof the valve plate and groove according to the present invention.

Figure 8 is a view similar to Figure 7 showingthe flow passage only inthe valve plate.

groove in the valve plate at the fulcrum.

Figure 11 is a fragmentary enlarged axial section of amodifiedform ofvalve plate with an outlet leakage groove from the con'trol chamber tothe outlet extending through the valve plate. I V

Figure 12 is a fragmentary elevation of theoutlet leak- Figure 13 is aview similar to Figure 11 showing a Figure 14 is a fragmentary elevationshowing the'outlet leakage grooveof Figure 13.

Figure 15 isia view similar'to Figure 11 showingraleakagerhole providedfrom the. control chamber to the. outlet.

. a 3 Figure 16 is a view similar to Figure showing a further variationin which a leakage hole is provided from the control chamber to theinlet leakage passage and thus to the outlet. I l v v Figure "17 'is afragmentary plan view of a further modification showing a seatarrangement for a valve plate having a hole through the valve plateclosed by the valve seat in seated position (Figure 18), but open fromthe inlet to the control chamber when the valve is open.

Figure 18 is a section on the line 18-18 of Figure 17, showing the valveplate and seat.

Figure 19 is a plan view of a modified form of steam trap according tothe invention, in which the control chamber and valve plate arerectangular.

Figure 20 is a section on the line 2020 of Figure 19.

Figure 21 is a diagrammatic axial section of a variant steam trapaccording to the invention in seated position.

Figure 22 is a detailplan view of the valve seat shown in Figure 21. j a

Figure 23 is a fragmentary section similar to Figure 21, showing thevalve plate in open position, but modified to show. a different form ofengagement with the bonnet from that which results in Figure 21.Figure24 is an enlarged fragment of the portion included within thecircle in Figure 23.

Figures 25 and 26 are views similar to Figure 24 but showing furthermodifications.

Describing in illustration but not in limitation and referring to thedrawings:

Steam traps of the character in which the forces incident to flow of thefluid directly cause opening and closing are well known in the art, asshown in McKee U.S. Patents 2,051,732; 2,127,649; 2,328,986; 2,622,886;2,724,399.

The present invention is concerned with improvements in steam trapswhich offer a number of distinct advantages in the art. i l i The steamtrap of the present invention is extremely light and relativelyinexpensive for its large discharge capacity. The. requirements forprecise machining are greatly reduced, and a relatively few simple partsmake up the I device.

' The closing forces are relatively very high, preventing thepossibility that the steam trap can remain open when it should beseated.

abrupt, with less likelihood of undesirable secondary" effects such asnoise and vibration. The steam trap of the present invention is'quiteinsensitive to the presence of dirt, and will tend to keep itself freefrom dirt accumulations as it operates.

In accordance with the invention, any leakage which occurs at the inletvalve does not result in increase in control chamber pressure, but iscarried directly to the 'rontlet through a flow passage, which may, forexample, be a groove in the valve plate or in the valve seat, or'inboth, and which preferably constitutes a combination of a concentriccircular and a circular eccentric groove, as later explained.

A further advantage of the invention is that the valve seat is readilymade replaceable so that in case of Wear a new valve assembly can beinserted bodily.

Continuous leakage is provided from the control chamher to the outlet,and this is suitably accomplished by providing a minimum limit offlatness and smoothness on the finish of the sealing parts, or byproviding grooves or scratches or holes in one or other of the sealingparts..

In the preferred embodiment, a lever type valve plate or disc' steamtrap is provided consisting of a concentricallydesigned circular valveplate which seals an inlet passage and an outlet passage in a seat toprovide for flow Unlike previous practice, the inlet passage and outletpassage are eccentric with-respect to the circular valve plate,

and by moment forces a tilting or lever action is developed on the valveplate which pivots or rolls around a circumferential point or line atthe edge of the round.

valve plate which is in diametral line with the center of the inletpassage and the outlet passage. This is c0mpletely different from thosesteam traps of the prior art in which the valve is lifted verticallywithout tilting.

It is important in the functioning of the steam trap of the presentinvention that there be leakage from the control chamber to the outleteven when the valve is closed. This is suggested by shading in variousof the drawings. Unless such leakage is provided the trap becomesinoperative due to air binding.

The form of Figures 1 to 7 illustrates an embodiment of the presentinvention which has a body' 30 consisting of any suitable metal such asstainless steel, steel, or bronze, having suitable threads 31 to connectto aninlet pipe at one end and suitable threads 32 to connect to anoutlet pipeat the other end.

' In the center of the body a suitably circular tapering valve seatrecess 33 receives a valve seat 34 which seals in the. valve seat recessby a gasket 35 in the bottom between respective bottom surfaces of theseat recess and the seat, and at an edge gasket 36 which engages inawedge groove between a downwardly inwardly converging surface 37 of thevalve seat recess and a downwardly out wardly converging wall 38 of thevalve seat, the gasket 36 being tightened by the bottom edge of a hollowbonnet .40 which is threaded at 41 into the body and which forms aninterior control chamber 42.

. The seat has a tapered portion 43 between the two seals which is insuitably spaced relation from a corresponding portion of the seat recessand has an outer circumferential wall 44 which is in close engagementwith the bore of the seat recess. The seat recess is bored at 45 andreceives a sleeve 46 which is pressed or otherwise secured in a.counterbore 47 in the seat which is in line with inlet passage 48extending through the seat, preferably near the center but not at thecenter, as later explained.

The inlet passage and the sleeve communicate with the inlet through abore 50 which is at least as large in cross section as the inletpassage.

' The valve seat also has an outlet passage 51 which desirably extendsdiagonally from a pjosition'near theouter circumference of the valveseat and communicates with "a 'bore 52 .which connects with the outletpiping.

A valve plate 53, suitably of disc or plate form, rests 'on the flatupper surface of the valve seat, and provides .of "the valve cooperateswith an inlet sealing flat 560i ring shape on the top of the seat. Thesesurfaces should make a reasonably good seal so as to keep leakage withinbou-nds when the valve is seated.

In the preferred embodiment there is a flow passage which communicatesbetween the outside of a sealing extends to the outlet. The valveplatehas .a suitably curved fulcrum surface 60 at its outer lower edgewhich gform as shownr permits lever action, as later explained, and theouter circumference of the valve plate tapers upward at 61 so as toprovideclearance from the inside of the control chamber when the valverocks, as shown in Figure 4. The

' top. 62 of the valve plate is conveniently made flat in this The inletpassage48 of suitably circular cross section is off center with respectto the center line of the valve plate'by a distance B shown in Figure 1.This offset ininto and out of a chamber including the valve plate.

troduces a moment and results in lever actionwith fulcrum efiectat Fadjacent the edge 60. The inlet leakage groove 58 surrounding thesealing flat aroundtheinlet inthe seat and the inlet leakage "groove 57.surrounding the inlet seat in the bottom of the disc will tend to conveyany leakage from the inlet when the valve is seated through the outletwithout going through the control chamber. The groove 57 is concentricwith the valve plate and is in line with the groove 58 in the seat onthe side of the inlet passage which is remote from the outlet passage.On the side of the inlet passage 48 which is adjacent the outlet passageor adjacent the fulcrum, the grooves 57 and 58 are offset as shown inFigure l by the groove width and the inner edge of the valve plategroove 57 registers with the outer diameter of the seat groove 58. Itwill be evident that the outlet port 5 1 is smaller than the inlet portand communicates with discharge.

The eccentric relations of the seat and disc grooves with respect to oneanother cause an increasing area under the valve plate which is atdischarge passage pressure toward the fulcrum so that the center ofpressure of this included area is offset slightly toward the fulcrumwith respect to the center of the valve plate. This any pressure in thecontrol chamber 42 above the valve plate will be effective at a smallermoment than the distance from the fulcrum to the center of the valveplate. Thisadds to the moment effect of the inlet passage eccentricityand gives a more pronounced lever action than would otherwise bepossible with higher over all performance and capacity for theparticular size of parts.

The numerical relations of the moment of the eccentric grooves aredeveloped by using the distances indicated on the diagram of Figure 5.

Let D be the inside diameter of the seat groove at distance L and D bethe outside diameter of the valve plate at distance L from the fulcrumF, and let L represent the mean eifective moment with respect to thepressure area A.

Then the relationship is aDaL TDaL;[Tm-401 and For the relations shownin Figure l the offset distance H equal to L L is very close to thusincreasing the effective moment of the inlet passage eccentricity by 50percent.

It will be evident that the effect of the inlet passage, the

size of the inlet passage, and the sizes of the grooves can .all bevaried to yield most effective results. If the inlet passage has adiameter equal to /3 of the effective valve plate diameter, the sealingcontact areas and the grooves are of proportions as shown in Figures 6and 7, where the fractions are fractions of the unit chosen for thediameter.

.thus permitting continuous discharge until a gaseous phase such assteam or air closes the valve. If steam closes the valve, condensationof this steam over a period of time can permit reopening in the absenceof leakage.

If, however, cold air closes the valve, in the absence of leakage thiswill prevent further cycling and it is for this reason particularly thatprovision for leakage from the control chamber to the outlet isessential.

' The operation will be understood by reference to Figure '1. Condensateflowing through .the eccentrically located inlet passage 48 exertspressure on the contacting valve plate area causing the valve plate tobe elevated as shown; in Figure 4. The eccentricity of the inlet passagefavors tilting rather than vertical lifting of the valve plate with afulcrum at F. Condensate is deflected by the bottom of the disc as shownin Figure 4 and is flows radially out Ward with a part entering thegrooves 57 and 58 and with velocity effects which extend to the outeredge of the valve plate where the condensate impinges on the controlchamber wall.

Flow into the control chamber reaches an equilibrium condition andpressure in the control chamber rises to a value which is related to thereconversion effectiveness of the velocity head to pressure head. Thediverted flow entering the inlet leakage passage grooves and part of thedirect stream passing to the outlet passage, are discharged through theoutlet.

Aside from the unbalance in the inlet passage flow resulting from itsoffset from the centerline of the valve plate, and the effect of thecenter of pressure area of the grooves in the valve plate and valveseat, the pressure gradient between the inlet orifice and the portopening leading to discharge, and a turning moment resulting from flowimpingement upon the angularly disposed undersurface of the disc,contribute to the positive effectiveness of the lever tilting of thevalve plate.

Where condensate is flowing through the steam trap, the effectivepressures to lift the valve plate are maintained at levels above thecontrol chamber pressure which is attainable and could producereclosure, and therefore the trap remains wide open, encouraging freedischarge. When gas or vapor enters the trap, however, the flow effectsare such as to develop a lower pressure under the valve plate consistentwith velocity reconversion to pressure above the valve plate toaccomplish valve closure. Since the difference in flow propertiesbetween one gas or vapor and another is slight, the practical effectsobtained when air or dry steam enters the trap are quite similar.

The conditions for opening. of the valve plate from the closed positioncan be developed in terms of the relations indicated on Figure 3 where P=inlet pressure p.s.i.

D =mean inlet orifice diameter subject to pressure P L ==moment of thepressure acting on the inlet area about fulcrum F P =mean pressure inthe control chamber above the valve plate D =mean valve plate diametersubject to the control chamber pressure P L =mean moment of the controlchamber pressure acting about the fulcrum F against the downstreampressure P When the valve lever is balanced with the. valve ready tolift, then P =approxirnately l9 P These calculations are based upon areameasurements to the seating surfaces with no allowance being made forleakage and pressure penetration between the seating surfaces. Thisdifference is to some extent cancelled out by corresponding areaincreases acting in both directions V 7 and" the actualvariation doesnot materially aflFect the result.

' With the valve leveror valve plate open, the chamber pressure forclosure can be determined, assuming that on saturated steam flow, a meanpressure P will be established below the valve plate as determined bythe critical ,pressure in the restricted downstream outlet passage 51leading to the discharge and the respective area relations of the inletand outlet restrictions.

The inlet passage of the proportional relations shown byFigure 3 is 4/3of the diameter of the outlet passage restriction, and with criticalflow of steam the throat pressure in the outlet passage will approximate0.56 P where P isthe pressure head of the downstream or dischargerestriction corresponding closely to the mean pressure below the valve.

If we assume flow. above the critical pressure is approximately afunction of VT 'or neglecting orifice coefficients C and C P,- P, A21

.By' substituting the value of the relation shown in Figure 3,

g 'P =0.87P The requirements for P may .be developed as follows:

' By substituting the value of 0.87 P for P and the ,practicalrelationsof Figure 3, it has been found that the value of P =89.5%Pwhich is the approximate mean minimum chamber pressure required to closethe steam trap valve plate on steam. On actual test it has been foundthat if the relations are such as to require a measured chamber pressureof "approximately 80 percent of the inlet pressure P for closure andpermit reopening of the valve when the chamber pressure P drops below20% of P, there will be quite acceptable performance. Proportions ofthis character are shown in Figures 1, 3 and 7.

Although the grooved valve plate and grooved seat have shown highefiiciency, it is possible to operate with a groove only in the valveplate or only in the seat for the purpose of creating an inlet leakagepassage, and in fact at a sacrifice of capacity and consistencyof-performance the device will operate without either type of groove. Iillustrate in Figure. 8 a steam trap havingra groove 57 only in thevalve plate and I show in Figure 9 a steam trap having a groove 58 onlyin the valve seat. Aside from the contribution which the grooves performto the promotion of lever action, they also serve to divert condensateflow into the outlet passage 51 much more efficiently and withpronounced efiiciency in discharge I capacity of the trap for therestricted proportions. Test results indicate that the capacity of theoutlet passage 51 is approximately double due to the presence of the 7:grooves as compared with operationswithout grooves.-

This may be explained by the interference effects of temperature alloysfor the valve plate and seat.

'conium or selenium 0.60 percent max. cated type 420 is a straightchromium stainless steel with high radial velocity with the enteringflow of the fluid into the discharge passage 51 in a normal direction.

- Since the steam trap is closed by the high chamber pressure developedduring. passage of an expanding gaseous fluid such as air or steam, itis important that there be a rate of leakage from the control chamber tothe outlet passage which is consistent with periodic reopening of thevalve plate to discharge accumulated condensate. If the flow of gaspersists as it may with excess of air in the lines, the valve plate willagain 'reclose for the duration of another cycle. This will occurrepeatedly until condensate reaches the steam trap, in which case thecondensate will be continuously discharged until a gas phase reaches thesteam trap.

It will be evident that in some steam trap applications, where rapidresponse to changing loading conditions is of great importance, thedelayed action. on air elimination may be detrimental. In other cases,however, where the condensate load is very slight andfairly constant andwhere the start-up period is of little consequence, as in tracer lineapplications, a trap of this character is very satisfactory. The trap ofthe present invention is particularly well suited to such applicationswhere the continuous discharge of vapor is objectionable and where it isadvantageousto sub-cool the condensate somewhat before its discharge, tominimize the release of flash steam and vapor.

Although the preferred embodiment of the invention uses a replaceableseat, which can be taken out bodily and replaced when it is worn, itwill of course be evident that a replaceable seat need not be usedunless desired.

The alloy making up the seat and valve plate will desirably be a wearresistant alloy, such as stainless steel, other corrosion resistingsteel, or bronze. The bonnet, although less important from a wearstandpoint, will likewise also be made of stainless steel, steel orbronze in the preferred embodiment. V,

The valve plate and seat are most desirably made from type 420 heattreated stainless steel (Rockwell C45) .with the seating surfaces groundto proper finish. The body and the bonnet are most desirably made oftype 416 stainless steel. For higher temperatures'it may be desirable touse heat treated type440 stainless steel or other high The types ofstainless steels mentioned are of course AISI types, and the specificcomposition limits involved are shown for example in the 1954 Supplementof the 1948 edition of Metals Handbook, published by The AmericanSociety for Metals, page 34, Table I of that Supplement. As showntherein, type 416 stainless steel is a straight chromium stainless steelwhich has 12 to 14 percent chromium and a minimum of 0.07percent'phosphorus or selenium, with carbon 0.15 percent max, manganese1.25 percent max, silicon 1 percent max and Zir- As likewise indi- 12 to14 percent chromium and a minimum of 0.15 percent carbon, in whichmanganese and silicon are each '1 :percent max, phosphorus 0.040 percentmax, and sulfur 0.030 percent max. Likewise type 440 is a straightchromium stainless steel with chromium from 16 to 18 percent, carbonanywhere from 0.60 to 1.20 percent depending upon which of three grades(440A, 440B and 440C) it is, manganese and silicon each 1 percent max,molybdenum 0.75 percent max, phosphorus 0.040 per- J cent max, andsulfur 0.030 max.

Figure 10 illustrates avariation in the device of the invention. In thisform the valve seat has its sealing surfaces slightly raised above thelowermost portion ofthe control chambenproviding an annular groove 63and an annular fulcrum shoulder .64 around the outer edge of the seat ashort distance in from the side of the control chamlar fulcrum groove 65which rides over the shoulder pergood results.

mitting' the valve plate 'to fulcrum where the fulcrum groove engagesthe shoulder. A form similar to Figure 110, but without the fulcrumgroove 65, has .also been tested and is operative. In this case theouter edge of the seating surfaceof the seat serves as thefulcrum.

In all of the forms of the invention using a circular valve plate andcircular control chamber, it will be evident that the valve is free toturn, and this distributes wear at the fulcrum. This is particularlyeffective in the form of Figure '10.

fl also provide in Figure 10 a central upwardly extending knob as whichin raised position of the valve loosely :fitsin a somewhat largerguiding socket 67 on the bottom .of the bonnet andtends to keep thevalve better centered when it is open. It also provides for convenientpickup and removal of the valve when servicing is required.

Leakage from the control chamber to the outlet passage to insurecontinuity of'operation may be controlled by regulating the grindingpractice used to finish the valve plate :and the valve seating surfaces.These surfaces should have a smoothness and flatness on the mating seatand valve plate surfaces which on engagement will provide fornoncontacting leakage clearance up to 10 microinches minimum andpreferably in the range of between 110 and 80 microinches, unless someother leakage means sisprovided. Experimentally it has been found thatsuch a finish can be obtained on a machine such as a Blanchard "SurfaceGrinder with grinding speeds and feeds selected -in accordance with thespecific material of construction. The specific finish largelydetermines the cycle. For an at average steam trapping application, acycle of 45 seconds i on dry steam as measured at 100 psi.initialpressure gives Some control of cycle time can also be exer ted byincreasing the control chamber size by using a wbonnet with moreor lesshollow space. I'fthis feature .is carried to excess, however, it .delaysclosing on steam and may be objectionable. i The machining finish at thevalve contact 70 from the control chamber to the outlet (or the groove71 if a groove is used) .should allow sufficient leakage so that inservice the pressure in the control chamber drops from 80 percent ofline pressure to 20 percent of line pressure in from 30 to 150 seconds,and preferably infrom 30 to 60 seconds.

The fit at 55 around the inlet may be a ground tight fit, butpermissibly it may be the same as the machining .xfinish in the surfacebetweenthe control chamber and the 'lou'tlet (for example at 70) Whenthe outlet sealing surfaces of the valve plate and .the valve seat matewith a substantially leak-tight joint, as when they are ground intogether or lapped together,

wit: is necessary to provide another leakage means in order that thissteam trapmay operate satisfactorily.

' Figures '11 and 12 show a valve seat 34', and a valve plate 53 whichhave. an accurately mating inlet sealing "surface '68, anoutlet sealingsurface 70, and a leakage .xgroove or .passage71 has been providedextending radiallyon theunderusurface ofthe valve plate which permitsicontrolled slight 'leakage from "the control chamber to theoutletpassage 5'1.

Figures 13 and 14 show a form somewhat similar to t-thatof Figures 11and 12,iexcept thatithe leakage groove .iorachannel is; provided at 7 1inthe outlet :seal surface 70 of the valve seat 34 :Figure shows 'avariantin which afleakage hole 72 is provided through the valvetplate353 from the control chamber to the outlet passage.

': rAsrit.isvdiificult to drill ar-hole fine enough to provide properleakage from the control chamber to the outlet ltpassage evenwhenwthevalve'plate is .clo sedpit is preferable as shown in Figure'16., to Idrillea larger hole as shown at 73 between the opposites'idesnof the valve plate 53 aijnil inewwith the groove .57 vandTalmostcompletely fill it with a wire 74- leaving the desired clearance.forleakage.

. seat and control chamber.

10 communication between the control chamber and the flow streamprovided at 75 when the valve plateis open before the stream reaches theoutlet passage. When the valve plate closes, however, a valve seatportion 76 closes thepassage 75' so that this communication to thecontrol chamber is no longer necessary.

This form of Figures 17 and 18 locates the perforation .75 between thetwo sides of the valve plate at a point between the inlet passage andthe outlet passage and provides improved communication to controlchamber pressurein addition to the relatively limited communicationaround the edges of'the valve plate when the plate is raised todischarge position. i p p In this form grooves 58' and 58 make the inletleakage passage around the inlet sealing flat to the outlet.

Good results have been obtained with a steam trap of this kind Figures19 and 20 show an alternate form of the steam trap of the inventionwhere the valve plate 77 is rectangular rather than circular. Althoughthe circular plate has many advantages from the standpoint of freeturning and distribution of wear at the fulcrum, other types of valveplates can be used. In this form the inlet leakage passage comprises anoval groove '78 in the seat which extends from a space around the inletsealing fiat 80 t0 the outlet.

It will be evident that in a steam trap of the prior art wherecommunication can be established between the inletand the controlchamber without direct communication with the outlet, leakage from theinlet into the control chamber will cause the steam trap to remainclosed, although operating conditions would make it desirable that thesteam trap open. This feature is prevented by the inlet leakage groove75; in the form of Figures 19 and.20 and by the other inlet ieakagegrooves shown, so that any leakage from the inlet goes to the outletrather than to the control chamber and it cannot build up pressure mightprevent valve opening.

f One advantage ofthe rectangular plate form resides .in thecomparatively long straight line rolling fulcrum contact provide at 81with the fulcrum surface of the This is to be compared with the verynarrow contact developed at the fulcrum in the case of a round valveplate in the form of Figures 1 to 7.

Thislong fulcrum contact tends to offset the disadvantage of continuedcontact at the same surfaces as compared with changing contact on thecircular valve plate.

We illustrate in the form of Figures 21 to 24 a modiffied steam trapconstruction in which the valve seat at the fulcrum position is machinedoff and forms a fulcrum line 82 which is transverse to the line ofcenters of the inlet and outlet passages and adjoining and beyond theoutlet passage. In this form inlet tube 46 and its counterbore have beeneliminated and a drainage bore 79, is

provided from thespace between the packings to the inlet leakage passage58. i

In this form the valve plate 53 in its upper limiting position where itengages the top of the control chamber does notpermit the taperingsurface 83 beyond the line fulcrum 82 to be engaged and the valve neverchanges fulcrum as it opens, although of course the valve plate whichmay be stated as follows:

it-Figures 1'713116 18 show steam traprpartsxwith pressurek 7(1) Thefulcrum relation is confined to the seat where ill. can beaccuratelypositioned with respect to the:in1et and outlet openings andto valve reclosure,

. addsto the closing moment in valve'opening force.

1 l therefore the device can be signed for stable operation.

' (2) The line fulcrum tends to support the valve plate laterally andprevents wobbling motion of the valve plate when open, thus givingsmooth and uniform discharge.

(3) Incorporation of all operating relationships in the valve seatpermits the valve plate to move more freely with respect to the valveseat without influencing performance and this therefore permits widerclearances between the valve plate and the inside of the bonnet. Thistends to reduce the cost of production of the valve plate and makes thedevice less sensitive to interference by dirt particles in the fluidstream. The engagement of the valve in open position at flat matingsurfaces with the interior of the bonnet makes the valve more stablewhen it is open, reduces wear and prevents stress concentration andpossible damage to the valve plate due to impact.

As previously explained in the McKee patents above referred to, thereare operating advantages in lengthening the lever arm as the valveopens. There is the further advantage in the present invention that thisfeature tends "to reduce the amount of wear greatly. j Figure 25 is amodification of the form shown in Figures 21 to 24 in that the linefulcrum 82 is tangent to and merges in a curve 87 beyond the linefulcrum which takes over the'fulcrum function as the valve opens. Insome cases this auxiliary fulcrum action can be produced more simply asshown in Figure 26rby providing a flat portion 88 beyond the linefulcrum 82 which engages the bottom 'of the valve plate as the valveopens and shifts the fulcrum to a remoteposition 90. This gives twofulcrum 's teps rather than an infinite number of fulcrum steps as inthe form of Figure 25.

It will be evident that the steam trap of the invention has a number ofvery definite advantages.

The lever action causes smooth valve opening and closing. .Themechanical advantage of the lever adds to the valve responding force andextends the time factor of the -response, eliminating the extremeabruptness of the dis charge'which occurs in some steam traps andminimizing the possibility that water hammer or other vibration or noiseeffects may result.

The lever action in the present invention causes relajtively largervalve lift at the inlet passage located near the outer end of the leverwith smaller lift atthe outlet passage located near the fulcrum. Thisproduces an increase in the intermediate pressure between the inlet andI outlet passage over that of a vertical valve lift and producescompensating effect for flow conditions favorable In other words itminimizes valve sticking and steam blow.

The lever action of the valve plate of the invention results in having alarger area of communication with the control chamber at the end of thelever near the inlet orifice and a decreased communication around thevalve plate as the fulcrum is approached. This causes a number ofdesirable effects:

(1) Circulation of flow above the valve plate occurs with flushing awayof dirt particle accumulations.

(2) A greater pressure restoration occurs from kinetic energy of flownear the end of the tilting lever valve plate where the moment effect isa maximum, thus assisting in reclosing. v

. (3) A pressure gradient exists between the control chamber space abovethe valve plate with a pressure drop toward the fulcrum. This stabilizeslever movement and proper relation to the (4) The reaction of the inletflow against the sloping surface of the valve plate in open position asdetermined by the lever movement causes lateral displacement toward thefulcrum. This reduces friction to a minimum since I mechanical contactis largely limited to very small relow coefficient.

tardation moments. 'Thus sensitive response and reclo sure are assured.

While the steam trap of the invention will operate without the need forthe groove in the seat or the groove in the valve plate or in both,these grooves establish communicating relief areas between the valveplate and the valve seat, which arevery advantageous for the following(1) Dirt accumulations have less effect on the operation in proportiontothe reduced seat contact area. (2)' The pressure relations for openingand closing are 'more positive and more consistent.

(3) Grinding of the seat and of the valve plate is facilitated andtolerances are less critical than where an entire continuous flatsurface is used.

(4)"Warp'age in heat treatment and in grinding are reduced.

' (5) The capacity for a given inlet and outlet passage area combinationis increased. The explanation for this seems to be that .where nogrooves are used the outward surface velocity of flow after impingementof the fluid on the flat valve plate tends to disrupt the flow in thenormal direction toward the outlet passage, thus causing a very Theintercommunicating circumferential grooves in the seat and the valveplate serve to channel a portion of the radial flow into the grooves allaround the'circumferential path where the diverted flow is shielded fromadverse velocity effects and cumulatively serves to feed the outletpassage at an approach to the normal c0- efficient.

In order to. obtain best results, the fulcrum, for example, in the formof Figures 1 to 7, has a fillet which in a 13/ 16 inch valve platediameter, is preferably of the order of a quarter inch radius. In anycase the fulcrum radius on the edge should not be less than inch so asto develop a rolling elfect. This rolling fulcrum has the followingadvantages:

' (1) It distributes wear over an area rather than a long line and thusgives longer life.

(2) By rotation the valve plate has a continuously changing fulcrumbearing area which further reduces wear and increases life.

(3)1By rolling action rather than knife edge pivoting the mechanicaladvantage is slightly increased with valve life which contributes toreclosing. This is shown at 60' in Figure 7.

valve.

(4) The wear on the side is distributed over an area, I

thus minimizing wear and adding to longer life. This is important inView of the area of fulcrum action on the seat. Since the seat is flatand well supported, it will stand extended wear from the area of rollingengagement.

The required size of the'valve plate and seat for a given capacity isgreatly reduced by reason of the advantages of the lever' action, therecessed seat and valve, and the are incurred because of a the followingadvantages:

(1) There is a simpler replacement of the seat and valve plate withoutchanging the piping.

(3') Minimum time is'lost due to ment to service the steam trap.

(2) Maintenance cost is reduced.

shut-down of equip- The lever action of the'rolling fulcrum valve platepermits operation in a vertical position with the valve "plate on thelower side rather than the top. This permits gravity drainage withprotection against freeze-up without introducing friction or causingvalve retardation.

In view of'our invention and disclosure variations and modifications tomeet individual whim or particular need will doubtlessbecome evident toothers skilled in the art, to obtain all or part of the benefits ofourinvention without copying the structure shown, and we, therefore,claim allsuch insofar as they fall within the reasonable spirit andscope of our claim.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is:

1. In a steam trap, a body having walls forming a control-chamber-havinga plurality of different sides joined together at-the edges 'thereof, afulcrum surface in the chamberand adjoining one such edge, walls formingan inlet passage of relatively large crosssectional area at one of'thesides of the control chamber at a location relativelyremote'fromthefulcrum surface, walls forming an outlet passage "of relativelysmaller cross sectional area entering *the said one side of the controlchamber at a location spaced from the inlet passage, a valve platefreely -t'iltal'ale 'in the control chamber, rocking about the fulcrumsurface, the centroid of the cross-sectional area of said inlet passagebeing farther away from the fulcrum than the centroid of the area ofsaid valve plate, said valve "plate having a seated position in whichthe inlet'passage is at leastnearly closed and-the portion of thecontrol "chamber onthe sideof the valve plate remote from the inlet andoutlet passages is nearly closed off from the outletpaud'having an openposition in which the inlet passage and the outlet passage communicatethrough the con- 'trol chamberandwith the portion ofthe control chamberon the side ofthe 'valve plate remote from the inlet and outletpassages, a first valve seat means cooperating with passagewithout'flowingthrough the portion of the control chamber on the .sideof the valve plate remote from the inlet and outlet passages, and asecond valve seat means cooperating with-the valve plate in seatedposition ofthe-valveplate-to-restrict flow from the portion of thecontrol chamber remote from the inlet and outlet passages to the outletpassage, there being continuous leakage means between the portion of thecontrol chamber remote from the inlet and outlet passages and the outleteven when the valve plate is seated.

2. A steam trap of claim 1, having a flow passage around the inlet whichcommunicates with the outlet pas sage in open and in seated position ofthe valve plate.

3. A steam trap of claim 2, in which the flow passage comprises a groovein the valve plate.

4. A steam trap of claim 2, in which the flow passage comprises a groovein the valve seat means.

5. A steam trap of claim 2, in which the flow passage is a groove in thevalve plate and also a groove in the valve seat means.

6. A steam trap of claim 2, in which the area beneath the valve platewhich is in communication with the outlet increases as the outlet isapproached.

7. A steam trap of claim 2, in which the flow passage comprises apassage which is annular but eccentric to the inlet passage.

8. A steam trap of claim 2, in which the flow passage comprises apassage which is in the seat and concentric with the inlet passage.

9. A steam trap of claim 2, in which the flow passage is a groove in thevalve plate and a groove in the valve seat means, said groovescoinciding at one position and diverging at the other positions.

I4 10. A-steamltrapof claim 9, in which the grooves coincide ataposition remote from the fulcrum and diverge closer to the fulcrum.

11. A steam-trap of claim 2, in which the control chamher is circularand the valve plate is circular and free to turn therein, the flowpassage includes a groove in the valve plate and a groove in the valveseat means, and

the valve seat means includes a sealing flat around the inlet passage,the grooves being each twice as wide as the sealing flat, and the centerof the inlet passage being olfset from the center of the valve plateaway from the fulcrum a distanceequal to one-half the groove width.

12. A steam trap of claim 1, in which the valve seat means comprises aremovable unit inserted in thebody.

13. A steam'trap ofclaim 1, having on the edge of the valve platewhich-engages the fulcrum surface, a curved surface on a radius notlessthan inch.

14. A steam trap of claim 1, in which the control chamber is circularand the valve plate is circular and free to-turn.

1 5. Asteam trap of claim 1, having a smoothness and flatness on themating seat and valve plate surfaces which -on engagement will providefor noncontacting leakage clearance up to 10 microinches minimum.

16. A steam trap of claim 15, in which the leakage clearance is in therange of between 10 and 80 microinches.

17. Asteam trap of claim 1, in which the valve plate is rectangular.

18. A steam trap of claim 1, in which the valve plate is circular, thefulcrum surface comprises a circular shoulder, and the valve plate has acircular recess which engages the circular shoulder.

19. A steam trap of claim 1, in combination with .a guiding knob on theside of the valve plate remote from the seat, and a guiding socket inthe control chamber engaging the knob in open position of the valveplate. 20. A steam trap of claim 1, in which there is a groove in thevalve'plate which provides the continuous leakage means from the controlchamber to the outlet passage when the valve plate is closed.

21. A steam trap of claim 1, in which there is a groove in-the valveseat means which provides the con tinuous leakage means from the controlchambertothe outlet'passage when the valve plate is closed.

22. A steam trap of claim 1, in which there isma hole throughthe .valveplate open from'the control chamber to the outlet passage when the valveplate is closed.

23. A steam trap of claim 1, in which there is a hole through the valveplate open from the inlet to the control chamber when the valve plate isopen, said hole being closed by the valve seat means when the valveplate is closed.

24. A steam trap of claim 1, in which the fulcrum surface extends alonga line fulcrum.

25. A steam trap of claim 24, in which there is an auxiliary fulcrumsurface merging with the line fulcrum and making fulcrum engagement whenthe valve lifts.

26. A steam trap of claim 25, in which the auxiliary fulcrum surface iscurved.

27. A steam trap of claim 25, in which the auxiliary fulcrum surface isflat.

28. A steam trap of claim 1, in which the top surface of the controlchamber makes flat engagement against the valve plate in open position.

29. A steam trap of claim 1, in which the leakage from the controlchamber to the outlet permits the control chamber pressure to drop frompercent of line pressure to 20 percent of line pressure in from 30 toseconds.

30 In a steam trap, a body having a circular control chamber, a circularvalve plate in the control chamber, an inlet passage into the controlchamber extending to one side of the valve plate in closed positioneccentric with respect to the control chamber, inlet valve seat meanssealingagainst the valve plate around the inlet'passage in seatedposition, an outlet passage into the control chamber extending from theone side of the valve plate in closed position, outlet valve seat meansrestricting flowfrom the control chamber into the outlet passage whenthevalve plate is seated while permitting continuous leakage, a fulcrumsurface at said one side of the control chamber at a positionremote fromthe inlet passage, said valve plate being free to tilt with one edgeresting on said fulcrum surface, and a flow passage extending from thespace around the inletvalve seat directly to the outlet passage when thevalve plate is closed.

31. A steam trap of claim in which the inlet passage is nearer thecenter of the control chamber than the outlet passage but the center ofthe inlet passage is on the outlet'passage.

32. In a steam trap, a body having a circular control chamber, acircular valve plate in the control chamber, an inlet passage into thecontrol chamber extending to one side of the valve plate in closedposition, inlet valve seat means sealing against the valve plate aroundthe inlet passage in seated'position, an outlet passage into the controlchamber extending from the one side of the valve plate in closedposition,'outlet valve seat means restricting flow from the controlchamber into the outlet passage when the valve plate is seatedjwhilepermitting continuous leakage, the inlet passage being nearer the centerof the control chamber than the outlet passage butthe center of theinlet passage being on the opposite side of the center of the valveplate from the outlet passage, and a fulcrum surfacein the controlchamber engaging said one side of the valve plate at a point remote fromthe inlet passage, said valve plate being free to tilt in the controlchamber about said fulcrum surface. I

33. A steam trap comprising walls forming a chamber for fluid underpressure, said chamber having an imperforate top and imperforate sideshaving a cross section which is circular about a, particular verticalaxis as a center, and said chamber having a bottom which has wallsforming an inlet opening eccentric of said axis, walls forming outletopening means, a fulcrum surface including a point on a line runningfrom the center of the inlet opening through the axis and located on theopposite side of the axis from the center of the inlet opening andan-ahnusurface than the center of said circular disc; the circular diskhaving two positions, a flat bottom-position and a second position inwhich it is inclined with the bottommost end'fulcruming on the fulcrumsurface, and having mating surfaces on the bottom of the disk which inthe bottom position of the disk mate with thebottom of the/chamberrespecively in the one case completely around the inlet opening insideof'the grooves and outlet opening, and in the other case completelyaround all said grooves and the inlet opening and outlet opening meansas a group, except that there are leakage means in said bottom positionof the disk at least between the inlet opening and thepart of thechamber which is above the disk, and the said grooves being incommunication with theoutlet opening in said bottom position of thedisk, and the disk being freely shiftable rotationally around its centerto an unlimited extent, subject only to the friction of fulcrum andmating surfaces.

'- 34. In a steam trap, a'housing having a control chamber, 'saidhousing including a flat disc seat plate which forms one wall of thecontrol chamber, a flat disc valve in the control chamber resting onsaid seat plate, the valve being permitted to tilt freely in'the controlchamber, inlet 'port means in the'seat plate located off center withrespect to the valve, a discharge,-a circular outlet groove in the seatplate surrounding the inlet portmeans and communicating with thedischarge, there being sealing areas on both sides of said groove, afulcrum surface for valve disc lift on the seatplate at a point ofmaximumedge remoteness from said inlet port means, and means providingslow leakage flow from the control chamber above the valve to thedischarge across the outlet sealing area. 5

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain Aug. 15, 1956

